Employee benefit plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Jan. 02, 2016		Jan. 03, 2015	Sep. 30, 2015
Components of net pension cost [Abstract]
Interest cost	$ 296		$ 316
Expected return on plan assets	(289)		(313)
Amortization of net loss	77		64
Net periodic benefit cost	84		67
Net cost of defined contribution plans	155		147
Net cost of all employee benefit plans	239		214
Movement in liability for pension benefits [Roll forward]
Liability for pension benefits at beginning of period	10,963		9,529
Interest cost	296		316
Expected return on plan assets	(289)		(313)
Plan contributions	(76)		(119)
Effect of exchange rate changes	(247)		(484)
Balance at end of period	10,647		8,929
Amounts recognized in balance sheet [Abstract]
Non-current liabilities	10,647		8,929	$ 10,963
Amounts recognized in accumulated other comprehensive loss [Abstract]
Actuarial loss, net of $16 and $47 tax benefit for the three and nine month periods, respectively, (2014: net of $13 and $39 tax benefit for the three and nine month periods, respectively)	59		50
Actuarial loss, tax benefit	18		$ 14
Estimated future benefit payments [Abstract]
2016	445
2017	514
2018	532
2019	540
2020	550
2021 - 2024	2,958
Level 1 (Quoted prices in active markets) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	3,222	[1]		3,238
Level 2 (Significant observable inputs) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	16,784	[2]		16,889
Level 3 (Unobservable inputs) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	0	[3]		0
Adept Strategy 9 Fund [Member] | Level 1 (Quoted prices in active markets) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	0	[1]		0
Adept Strategy 9 Fund [Member] | Level 2 (Significant observable inputs) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	12,356	[2]		13,044
Adept Strategy 9 Fund [Member] | Level 3 (Unobservable inputs) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	0	[3]		0
Schroder Matching Plus Nominal and Index Linked Liability Driven Investment Swap Funds [Member] | Level 1 (Quoted prices in active markets) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	0	[1]		0
Schroder Matching Plus Nominal and Index Linked Liability Driven Investment Swap Funds [Member] | Level 2 (Significant observable inputs) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	4,428	[2]		3,845
Schroder Matching Plus Nominal and Index Linked Liability Driven Investment Swap Funds [Member] | Level 3 (Unobservable inputs) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	0	[3]		0
U.S. Equity Funds [Member] | Level 1 (Quoted prices in active markets) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	368	[1]		350
U.S. Equity Funds [Member] | Level 2 (Significant observable inputs) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	0	[2]		0
U.S. Equity Funds [Member] | Level 3 (Unobservable inputs) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	0	[3]		0
U.S. Mutual Funds and Fixed Income Funds [Member] | Level 1 (Quoted prices in active markets) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	2,589	[1]		2,557
U.S. Mutual Funds and Fixed Income Funds [Member] | Level 2 (Significant observable inputs) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	0	[2]		0
U.S. Mutual Funds and Fixed Income Funds [Member] | Level 3 (Unobservable inputs) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	0	[3]		0
Cash [Member] | Level 1 (Quoted prices in active markets) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	265	[1]		331
Cash [Member] | Level 2 (Significant observable inputs) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	0	[2]		0
Cash [Member] | Level 3 (Unobservable inputs) [Member]
Fair Value of Plan Assets [Abstract]
Fair value of plan assets	0	[3]		$ 0
U.S. Defined Benefit Plan [Member]
Estimated future employer contributions [Abstract]
Employer contributions	0
Estimated future employer contributions in current fiscal year	200
U.K. Defined Benefit Plan [Member]
Estimated future employer contributions [Abstract]
Employer contributions	76
Estimated future employer contributions in current fiscal year	$ 445
U.K. Defined Benefit Plan [Member] | Adept Strategy 9 Fund [Member]
Estimated future employer contributions [Abstract]
Defined benefit plan, actual plan asset allocations	80.00%
U.K. Defined Benefit Plan [Member] | Schroder Matching Plus Nominal and Index Linked Liability Driven Investment Swap Funds [Member]
Estimated future employer contributions [Abstract]
Defined benefit plan, actual plan asset allocations	20.00%

[1] Level 1 inputs are quoted, unadjusted prices in active markets for identical assets or liabilities at the measurement date. The Company's pension plan financial assets in U.S. Equity Funds, Mutual Funds and Fixed Income Funds are Level 1 assets.

[2] Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. The Company's pension plan financial assets held in the Adept Strategy 9 Fund and the Schroder investments are Level 2 assets. The Company uses the Net Asset Value to determine the fair value of underlying investments which a do not have readily determinable fair value; and b prepare their financial statements consistent with the measurement principles of an investment company. The Funds are not exchange traded. The Funds are not subject to any redemption notice periods or restrictions and can be redeemed on a daily basis. No gates or holdbacks or dealing suspensions are being applied to the Funds. The Funds are of perpetual duration.

[3] Level 3 inputs are unobservable inputs for an asset or liability. The Company currently does not have any Level 3 pension plan financial assets.